By Marwan Nesicolaci
First used to disinfect drinking water in Jersey City, N.J., in 1908, chlorine technology has eliminated most waterborne diseases in the U.S. The most common disinfectant for drinking water and wastewater, chlorine is also used for disinfection and as a biocide in numerous industries.
Chlorine Gas Applications
The disinfection of potable water is one of the most common chlorine applications. In addition to being a potent but economical disinfectant, gas chlorination also leaves a residual, which the U.S. Environmental Protection Agency requires in the water distribution system to prevent contamination in the pipelines. Gas chlorine is also used to disinfect treated wastewater and reclaimed water.
Many industries also use gas chlorine for various applications, including cooling water and intakes, aluminum or gold fluxing, pulp and paper, food and beverage, rubber glove manufacturing, flour bleaching, and more.
Chlorine gas has been in use for over 100 years. The vacuum-operated solution feed technology offers maximum safety and allows flexible designs for different control strategies at multiple feed points. It is usually the least expensive method of chlorination for disinfection or biocide control, provided that the chemistry does not produce harmful byproducts.
Finding the Right Disinfection Technology
To find the best disinfection technology, the application should be carefully reviewed and questions asked, including:
• What are you trying to accomplish?
• What are the target microorganisms?
• What is the control strategy?
• Are disinfection byproducts an issue?
• What is the budget for capital expense and operating expense?
• Who will be using the system and what is the operational degree of
• What safety issues must be considered?
Working with a technical expert for every application is crucial; each technology has advantages and disadvantages.
Optimizing Installed Assets
First, it’s important to use reputable, reliable equipment suppliers. Be sure you have great support from your local representatives or manufacturer after-sales support for spare parts and technical assistance.
You should also complete a site safety assessment. Be sure the facility has an up-to-date Hazard and Operability Study (HAZOP), Risk Management Program, and Training Program. Consider implementing container shut-off systems or scrubbers.
Many chlorination technology applications are well suited to chlorine gas feed systems, and the cost is usually an advantage. On a global scale, we have not seen a drop in the market for chlorine gas feed systems in favor of alternative technologies. There are thousands of gas chlorination installations providing reliable service. Large gas systems are still the standard for disinfecting potable water around the world.
Safety concerns have prompted some to consider replacing gas chlorine with alternative disinfection methods. But it’s important to note that current U.S. regulations require strict risk management and process safety management programs. Operators of chlorine gas systems are highly trained, and stringent safety procedures are in place to prevent any problems. Emergency gas scrubbers and container shut-off systems have further enhanced the safety of using chlorine gas.
When chlorinated byproducts are an issue, other disinfection technologies should be considered. These include chlorine dioxide, chloramination, ultraviolet radiation, ozonation, advanced oxidation processes (AOP), and peracetic acid (PAA).
Room for Innovation
The basic method of feeding gas chlorine — vacuum-operated solution feed — hasn’t changed since it was invented in 1960. Despite its long history of reliable, robust disinfection, there is still room for innovation with this tried-and-true technology. It may not be as sexy as launching a brand-new technology, but there are some incremental developments happening right now. Improvements are typically related to features, instrumentation, and control. These improvements deliver operating benefits for customers who, based on their current application, still use gas feed products. WW
About the Author: Marwan Nesicolaci is senior vice president of global sales and operations for Asia and UK for De Nora Water Technologies located in Colmar, Pa. He is a board member of the Water and Wastewater Equipment Manufacturers Association (WWEMA). For more information about WWEMA, please visit www.wwema.org.